Treatment of hydrocarbon oils



Dec. 22, 1936. o. BEHIMER TREATMENT OF HYDROCARBON OILS Filed Oct. 22, 1932 FURNACE l7 FRACTIONATOR FURNACE INVENTOR OTTO BEHIMER BY JZQW ATTOR Y FURNACE FURNACE 7 Patented Dec. 22, 1936 UNITED STATES PATENT OFFICE TREATMENT OF HYDROCABBON OILS poration of Delaware Application October 22, 1932, Serial No. 639,035

2 Claims.

This invention particularly refers to an improved process and apparatus for the conversion of hydrocarbon oils of relatively wide boiling range, such as crude petroleum, wherein said oil 5 is separated into a plurality of selected fractions,

each of which is subjected to independently coni;rolled conversion conditions most suitable for the If production of maximum yields of good quality motor fuel. in As a further feature of the invention intermediate conversion products of the cracking operation are separated into fractions corresponding in boiling range to certain selected fractions of the charging stock and each fraction of said 16 intermediate conversion products is subjected to conversion together with the corresponding fraction of the charging stock.

In one of its more specific embodiments the invention may comprise heating a charging stock '20 such as crude oil or other hydrocarbon oil of wide boiling range and, introducing it into a fractionating column wherein its substantial vaporization is effected and the vapors are separatedlby fractionation into three fractions comprising (1) gasoline and naphtha having an end, boiling point of approximately 400 to 450 F., (2) kerosene having an end boiling point of approximately 550 to 600 F. and '(3) bottoms with an initial boiling point of 550 to 600 F. and containingfll h'e" fractions of the charging stock boiling, above this point, subjecting the gasoline and naphtha fraction to reforming at a temperature of 950 to 1050" F or thereabouts and a superatmospheric pressure of from approximately 500 to 1000 35 pounds per square inch, separately subjecting the kerosene fraction to a conversion temperature of 900 to 1000 F. or thereabouts at a superatmospheric pressure of approximately 300 to 500 pounds per square inch, separatelysubjecting the 40 bottoms to a conversion temperature of 850 to 950 F. or thereabouts at a superatmospheric pressure of approximately 100 to 300 pounds per square inch, separating the resulting vaporous and residual conversion products, subjecting the vapors to fractionation whereby a motor fuel of the desired boiling range and of high antiknock value is recovered as the final light distillate product of the system and whereby the higher boiling insufliciently converted components are 50 condensed as reflux condensate and the reflux condensate separated into fractions boiling above and below approximately 550 to 600 F., returning the low boiling fraction of the reflux condensate to further conversion together with the kerosene fraction of the charging stock and returning the higher .hoiling fraction of the reflux condensate to further conversion together with the bottoms from the charging stock.

It should be understood that charging stocks of difierent characteristics may be separated into any number of different selected fractions, each of which requires separate treatment under different conversion conditions as provided by the features of the present invention, and the invention is therefore not limited to the separation and separate treatment of any specific fractions but the operation may be varied to suit the requirements of the charging stock.

The accompanying diagrammatic drawing illustrates one specific form of apparatus in which are embodied the features of the present invention, and the following description of the drawing includes a description of the operation of the process as it may be practiced in the apparatus illustrated.

Referring to the drawing, the crude oil or other charging stock of relatively wide boiling range is supplied through line I and valve 2 to pump 3, from which it is fed through line 4 and valve 5 into heating coil 6, which is located in a furnace I of any suitable form, by means of which the oil is heated to a temperature'suflicient to insure its substantial subsequent vaporization at the de sired pressure and the heated oil is discharged through line. 8 and valve 9 into 'fractionating column 10. The charging stock may of course be preheated in any well known manner not illustrated in the drawing prior to its introduction into the heating coil, when so desired.

The heated oil may enter fractionator ID in substantially vaporized state, or is substantially vaporized in this zone, and when superatmospheric pressure is employed in heating coil 6 it is preferably released or substantially reduced in fractionator H] in order to assist vaporization of the oil.

The heated oil supplied to fractionator I0 is separatedin this zone into any desired number of selected fractions which may be removed as an overhead vaporous stream, side streams from suitable points in the fractionator, and as bottoms from the lower portion of the fractionator. In the case illustrated the charging stock is divided into three streams. The overhead vaporous product withdrawn, from the upper portion of the fractionator passes through line II and valve [2 to pump or compressor l3, by means of which it is supplied through line H and valve l5 to heating coil l6 wherein it is subjected to the desired optimum conditions of conversion temperature,

pressure and time, the required heat being supplied from furnace ll of any suitable form. The

heated products are discharged from heating coil l6 through line I8, valve i9 and line 39 into vaporizing chamber ilo That fraction of the charging stock removed as a side stream from fractionator 10 passes through line 20 and valve 2! to pump 22, from which it is fed through line 23 and valve 24 into heating coil 25 to be there subjected to the desired optimum conversion conditions of temperature, pressure and time with heat for the conversion reaction supplied from a furnace 26 of any suitable form. The'heated conversion products are discharged from heating coil 25 through line 21, valve 28 and line 39 into vaporizing chamber dl. The remaining fractions of the charging stocks or bottoms are removed from the lower portion of the fractionator through line 29 and valve 30 to pump M to be fed through line 32 and valve 33 to heating coil 34, which is located in a suitable form of furnace 35, which furnishes the heat required to subject .the oil in heating coil 34 to the desired conversion temperature under the optimum conditions of pressure and time. The heated oil is discharged from heating coil 34 through line 36 and valve- 31 into a reaction chamber 38, which is preferably operated at a substantial superatmospheric pressure and which, although not illustrated in the drawing, is preferably well insulated to prevent the excessive loss of heat by radiation so that the oil from heating coil 3d, and more particularly the vaporous products from the heating coil, may be subjected to continued conversion in this zone for a predetermined time while the liquid conversion products from the heating coil, which gravitate more rapidly to the outlet from the chamber, may be removed therefrom without being subjected to the continued conversion time afforded the vapors in this zone. Both vaporous and residual liquid conversion products are withdrawn from the lower portion of chamber 38 through line 39 and valve 40 into vaporizing chamber 4|.

It will be understood that, although not illustrated in the drawing, the conversion products from heating coils l6 and 25 may also be subjected to continued conversion time in chamber 38 or in similar individual chambers not illustrated in the drawing. However, the low boiling nature of the fractions supplied to heating coils l6 and 25 or, more particularly, the absence of any appreciable quantity of high boiling or high coke-forming materials in these fractions usually obviates the necessity of discontinuing heating of the oil before the'desired degree of conversion is completed and to complete the conversion, particularly of the vaporous components of the oil, in an unheated reaction chamber, which practice is desirable in the treatment of higher boiling oils in order to avoid coking of the heavy end products. The total conversion time required for the optimum treatment of the light fractions may therefore be allowed in the heating coils without employing a reaction chamber and this type of operation is the one illustrated in the drawing.

The total vaporous and liquid conversion products from heating coils l6 and 25, as well as from heating coil 34 and reaction chamber 38, are discharged as already described into vaporizing chamber 4|, which is preferably maintained at a substantially reduced pressure relative to the pressures employed in the heating coils and the reaction chamber. The latent heat liberated by the reductionin pressure serves to effect further aoeaere vaporization of the liquid conversion products in chamber 4| and final separation of vaporous and residual conversion products is effected in this zone. The operating conditions of the process may be controlled to accomplish the recovery of any desired type of residual product in chamber ii ranging from good quality, residual liquid through the various stages of solid or semi-solid asphaltic or pitchy materials to substantially dry petroleum coke. Residual liquid, when produced, may be removed from chamber ii through line 42 and valve 33 to cooling and storage or any desired further treatment. When substantially dry coke is the residual product of the process it may be allowed to accumulate in chamber 6|, to be removed therefrom after the operation of the chamber is completed, and, when desired, a plurality of chambers similar to chamber 4|, but not illustrated, may be utilized to provide additional space for the deposition of coke and may be either alternately or simultaneously operated. Line 82 and valve 43 may also serve as a means of introducing water, steam or other suitable cooling medium into the bed of coke in chamber 4! to hasten cooling and facilitate cleaning of the chamber.

Vaporous conversion products pass from chamher GI through line 46 and valve 45 to fractionator 66, wherein their insufficiently converted components are condensed as reflux condensate and separated into selected fractions for the further treatment, as will be later more fully described, while vapors of the desired end boiling point, preferably within the range of motor fuel and of good antiknock quality, are withdrawn together with uncondensable gas from the upper portion of the fractionator through line 41 and valve 68, are subjected to condensation and cooling in condenser 49, from which the resulting distillate and uncondensable gas passes through line 50 and valve 5| to be collected in receiver 52. Uncondensable gas'may be released from the receiver through line 53 and valve 54. Distillate may be withdrawn from the receiver to storage or to any desired further treatment through line 55 and valve 56.

In the case illustrated, the insufliciently converted components of the vaporssupplied to fractionator 46, are withdrawn therefrom as two selected fractions, one of which is recovered as a side stream or streams from one or any number of a plurality of selected points in the fractionator such as provided by lines 59, 59 and 59", controlled by valves 60, 60' and 60", respectively, passing therefrom through line 5'! and valve 58 to pump 6|. This fraction of the reflux condensate or insufficiently converted components of the cracked vapors will correspond, in the case illustrated, to the boiling range of that fraction of the charging stock withdrawn as a side stream from fractionator Ill through line 20 and valve 2| to pump 22, as already described, and the two streams are commingled by directing the oil from pump 6| through line 62 and valve 63 into line 23, to be discharged therefrom, together with the commingled oil from pump 22, through valve 24 in line 23 into heating coil 25. In this manner corresponding fractions of both the charging stock and the intermediate conversion products are subjected to conversion under the optimum conversion conditions for fractions of this particular boiling range in heating coil 25.

The higher boiling components of the inter point corresponding to the initial boiling point of the bottoms from the charging stock, are-with- .drawn from the lower portion of the fractionator 46 through line 64 and valve 65 to pump 66, wherefrom they are fed through line 61 and valve 68 into line 32, commingling therein with the bottoms withdrawn from fractionator l0, as already described, and passing therewith to further conversion under the desired conditions in heating coil 34.

It will be understood that, as already stated in connection with the separation of the charging stock into various fractions, the intermediate or insumciently converted products of the cracking operation may also be divided into any desired number of selected fractions which preferably correspond approximately in boiling range to various selected fractions of the charging stock and are each subjected to further conversion together with said selected fraction of the charging stock of corresponding boiling range.

The temperature to which the charging stock is heated prior to its separation into selected fractions is sufficient to effect its subsequent substantial vaporization without appreciable conversion and may range, for example, from 600 to 750 F. or thereabouts with any desired pressure in the heating coil, ranging for example from substantially atmospheric to pounds or more per square inch. The separating and fractionating column to which the heated charging stock is supplied is preferably operated at substantially atmospheric or relatively low superatmospheric pressure below 100 pounds or thereabouts per square inch. The conversion conditions to which the various fractions of the charging stock and thecorresponding intermediate conversion products of the process are separately subjected may range, for example, from 800 to 1100 F., preferably with substantial superatmospheric pressures in the various heating coils ranging, for example, from 100 to 1000 pounds or thereabouts per square inch. Preferred conversion conditions'of temperature and pressure for various specific fractions in a system such as illustrated and above described have previously been mentioned. The reaction chamber, as already indicated, is operated at a substantial superatmospheric pressure which may be substantially equalized with or somewhat reduced relative to that employed in the communicating heating coil. The vaporizing or coking chamber is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber. The fractionating, condensing and collecting portions of the cracking system may be operated at a pressure substantially-equalized with or somewhat reduced relative to the pressure employed in the vaporizing or coking chamber.

As a specific example of one of the many possible operations of the process of the present invention, the raw oil charging stock is a Smackover crude of about 27 A. P. I. gravity, which is heated to a temperature of approximately 600 F. at a superatmospheric pressure of about 100 pounds per square inch and then introduced into the iractionating and separating column, from which gasoline and naphtha,'-kerosene and bottoms are separately withdrawn, the gasoline and naphtha iraction, having an end boiling point of approximately 450? F. andcomprising about. 20per cent of the charging stock, is subjected-in a heating coilto a conversion temperatureof approximately 1000" F. at a superatmospheric pressure "of. about 800 pounds persquare inch and the products are discharged into the reduced pressure vaporizing chamber. The kerosene fraction, amounting to an additional 22 per cent or thereabouts of the charging stock and having an end boiling pointv of approximately 600 F., is subjected in a separate heating coil to a conversion temperature of about 975 F. at a superatmospheric pressure of approximately 500 pounds per square inch and the products are then introduced into the reduced pressure vaporizing chamber. Bottoms from the topping operation having an initial boiling point of approximately 600 F. are subjected in a separate heating coil to a conversion temperature of approximately 925 F. at a superatmospheric pressure of about 300 pounds per square inch and are discharged into a reaction chamber operated at about the same pressure, wherein their vaporous components are subjected to continued conversion and from which the total vaporous and liquid products are discharged 'into the reduced pressure vaporizing chamber. The vaporizing chamber is operated at a superatmospheric pressure of about 50 pounds per square inch, which pressure is substantially equalized in the succeeding fractionating, condensing and collecting portions of the cracking system. A distillate of about 400 F. end boiling point is collected as the final motor fuel product of the process from the fractionator of the cracking system. The intermediate conversion products of the process condensed in the fractionator of the cracking system are separated into fractions boiling above and below approximately 600 F. The 400 F. to 600 F. fraction is returned for further conversion to the same heating coil to which the kerosene fraction of the crude is supplied, and the remaining higher boiling fractions, havirm an initial boiling point of approximately 600 F., are returned for further conversionto the same heating coil to which the bottoms from the crude oil topping operation are supplied. This operation may yield, per barrel of charging stock, about '72 per cent of motor fuel having an antiknock value equivalent to an octane number of approximately 78 and about 15 per cent of residual oil, the remaining 13 per cent, or thereabouts, being chargeable principally to uncondensable gas. I

When the operation is conducted on a nonresidum basis, producing petroleum coke instead of liquid residue, the yield of motor fuel may be somewhat increased without depreciating its antiknock value and usually with a somewhat increased yield of gas.

I claim as my invention:

1. A process for producing motor fuel which comprises fractionating crude oil containing natural gasoline and separating the same into a vaporous fraction containing the natural gasoline and naphtha, an intermediate liquid fraction, and bottoms; independently subjecting the vaporous fraction, the liquid fraction and the bottoms to conversion conditions of temperature and pressure and subsequently commingling the same, separating the commingled hydrocarbons into vapors and residue, fractionating the vapors independently of the charging oil and separating therefrom a light reflux and a heavy reflux, retreatinglthe light and heavy refluxes in admixturewith said liquid fraction and bottoms respectively and finally condensing the fractionated vapors.- I

' and separating therefrom a light fraction containing natural gasoline hydrocarbons, an intermediate fraction and' a heavy fraction, independently subjecting the light fraction, the intermediate fraction and the heavy fraction to conversion conditions of temperature and pressure in separate heating zones, subsequently discharging the thus heated fractions into a separating zone and separating the commingled hydrocarbons into vapors and residue in the separating zone, dephlegmating the vapors independently of the crude petroleum undergoing fractionation and separating therefrom a light reflux and a heavy reflux, retreating the light and heavy 5 refluxes in admixture with said intermediate fraction and heavy fraction respectively, and finally condensing the fractionated vapors.

- OTTO BEHIMER. 

